1. Field of the Invention
The present invention relates to a liquid discharge recording head such as an ink jet recording head. Such a head is applied to a liquid discharge recording apparatus such as an ink jet recording apparatus performing recording operation by discharging liquid.
2. Description of the Related Art
Conventionally, the ink jet recording apparatus has relatively low running cost and can be downsized and further readily support color image recording using plural colors of inks. Accordingly, the apparatus has widely been used for a computer-related output apparatus and commercialized.
In recent years, it is desired that a recording head with the wide recording width in line recording in order to realize high resolution image recording at further high speed. More specifically, the recording head of 4 to 12 inches are required.
For example, Japanese Patent Application Laid-Open No. 2007-296638 discusses a recording head with a wide recording width. FIG. 10 illustrates an exploded perspective view of the recording head disclosed in Japanese Patent Application Laid-Open No. 2007-296638. In this recording head, a plurality of recording element substrates 1001 is arranged on a supporting plate 1200 in a staggered arrangement. An electric wiring board 1300 is disposed on the supporting plate 1200 and electrically connected to each recording element substrate 1001. Further, the supporting plate 1200 is connected to an ink supplying member 1500 and forms an ink jet recording head.
However, according to the recording head with such a configuration, the electric wiring board is formed from a resin film typically including polyimide; the linear expansion by heat, or the amount of expansion and contraction, is considerably larger than that of a supporting plate made from ceramic. A configuration where a metal plate including SUS is cemented on an electric wiring board is also disclosed. However, the difference of linear expansion is not well resolved; the expansion and contraction about three times that of supporting plate made of ceramic occurs. In general, the amount of expansion of a component under a temperature difference relates to the coefficient of linear expansion of the component×the difference of temperature×the length of component. Thus, the recording head with a wide recording width has significantly large electric wiring board (large in the longitudinal direction). This configuration considerably enlarges the difference in expansion and contraction by heat around the ends of the recording head.
Therefore, the amounts of change in dimension by heat particularly increase between the recording element substrates at the longitudinal ends of the recording head and the electric wiring board. Accordingly, large tensile and compression stresses are applied to a component (for example, Au wire) connecting the recording element substrate and electric wiring board. A problem may thus arise in terms of securing electric connectivity and reliability of electric connection.